Radiance can generate more orbs, increase survivability, decrease the cooldown of grenades/melee, increases the power of Scorch by 70% and allows you to self-revive. Nova Bomb has better mob killing potential. Energy Drain has two different methods for survivalibity (speed or health regen), and then there's bloom. Warlocks can also have higher armor than Hunters with high recovery. Their grenades are better for dealing with crowds.